[Other] Imaging characteristics of osteitis condensans ilii. A follow-up study Copy

Objective: To evaluate the diagnostic ability of combined clinical and MRI findings in a cohort of patients initially diagnosed with axial spondyloarthritis (axSpA) and to detect potential patients with osteitis condensans ilii (OCI) for further analyses.

Materials and methods: We conducted a retrospective follow-up study of 129 consecutive patients aged ≥ 18 years (49 women/80 men) diagnosed with axSpA during the period 2012-2023. Uniform baseline MRI of the sacroiliac joints (SIJ) and spine with concomitant radiography and/or CT were reassessed by an experienced radiologist using fulfillment of thresholds for SIJ MRI changes consistent with axSpA and a global assessment of all imaging material. Clinical and biochemical findings at baseline and during follow-up were reevaluated and in combination with imaging findings used as a reference standard for axSpA and OCI changes, respectively. Imaging findings consistent with OCI were confirmed by a second experienced radiologist and OCI imaging characteristics were systematically assessed.